1. Principles of Flight Learning Outcome 3
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Principles of Flight
Learning Outcome 3
Know the principles of flight and control for gliders
Identify forces acting on a glider in flight
Revision 2.00

2. Principles of Flight
Revision

3. Questions for you …..

4. What happens to lift when a wing is stalled?
a. Lift increases as the angle of attack decreases
b. Lift decreases as the angle of attack increases
c. Lift is greatly reduced
d. Lift remains unchanged

5. The critical angle of attack is generally about ....
a. 5o
b. 15o
c. 25o
d. 35o

6. 3. Which of the following will NOT reduce stalling speed?
a. Extra weight
b. Larger wing area
c. Flaps lowered
d. Flaps raised

7. Gliding

8. Gliding
Objectives:
List and describe the forces acting on a glider during balanced flight
State the effect of wind on the distance travelled over the ground
Explain the effects of airbrakes on glide performance
Understand the gliding angle (angle of attack)

9. Are these forces in balance for straight and level flight?
What are the Forces acting on a Powered Aircraft?
Lift
Thrust
Drag
What forces are present in straight and level flight?
Where do these forces act through? Show Centre of Gravity (CG).
Could show CG using an odd shaped object.
Weight

10. What would happen if we had NO thrust?
Lift
Thrust
Drag
What forces are present in straight and level flight?
Where do these forces act through? Show Centre of Gravity (CG).
Could show CG using an odd shaped object.
Weight
What do we need to do to overcome drag?

11. Lift Drag Weight What forces are present in straight and level flight?
Where do these forces act through? Show Centre of Gravity (CG).
Could show CG using an odd shaped object.
Weight

12. Lift Drag Weight What forces are present in straight and level flight?
Where do these forces act through? Show Centre of Gravity (CG).
Could show CG using an odd shaped object.

13. Gliding speed The car can coast down the hill with no engine How?
GRAVITY
Can we use gravity to fly a glider?

14. Gliding speed A glider uses gravity to descend
The airflow over the wing
produces lift
How do we control the speed?

15. Lift
Speed
If the nose is raised, what will happen?
Lift and speed reduce
The rate of descent also reduces

16. Lift
Speed
If the nose is lowered, what will happen?
Lift and speed increase
The rate of descent also increases

17. Remember:
If you fly too slowly lift will be lost and the glider will stall
If you fly too quickly the rate of descent will be high

18. What is the BEST angle to fly at?
How far will a glider travel?
The flatter the gliding angle, the further the distance over the ground
The steeper the gliding angle, the shorter the distance over the ground
What is the BEST angle to fly at?

19. Lift/Drag ratio α CL CD α 0°

20. The Pilot’s Notes will give information on gliding speeds
For example:
A Viking glider’s angle is about 1 in 35
Therefore, from a height of 3,280 ft (1 kilometre), in still air, it will travel about 35 kilometres

21. The effect of wind
What will happen when flying at the same airspeed and angle of attack?

22. What will happen when flying at the same airspeed and angle of attack?
Still air
Headwind
Tailwind

23. The effect of the airbrake
When the airbrake is opened, what happens to the drag?
The drag increases
What must be done to maintain airspeed?
Lower the nose

24. Airbrake in
Airbrake out
= steeper descent
+ shorter ground distance

25. Airbrakes

26. Any questions?

27. Questions for you …..

28. Name the forces acting on a glider in normal flight
a. Force, weight and lift
b. Drag, weight and thrust
c. Drag, weight and lift
d. Drag, thrust and lift

29. How does a glider pilot Increase airspeed?
a. Operate the airbrakes
b. Lower the nose by pushing the stick forward
Raise the nose by pulling the stick back
d. Lower the nose by pulling the stick back

30. 3. A Viking glider descends from 1640 ft (0. 5 km)
3. A Viking glider descends from 1640 ft (0.5 km) How far over the ground does it travel (in still air)?
a km
b. 35 km
c. 70 km
d km

31. 4. When flying into a headwind, the distance covered over the ground will .....
a. Be the same
b. Decrease
c. Increase
d. Take you to Burger King